Pepto Bismol (Bismuth Subsalicylate) Dosing
For adults and children 12 years and older, the FDA-approved dose is 2 chewable tablets (524 mg bismuth subsalicylate) every 30-60 minutes as needed, not exceeding 8 doses (4.2 g) in 24 hours, with treatment duration limited to 2 days for diarrhea. 1
Adult Dosing
Standard Indications (Diarrhea, Upset Stomach, Heartburn, Indigestion, Nausea)
- Immediate dosing: 2 chewable tablets every 30 minutes OR 4 chewable tablets every hour for diarrhea 1
- Alternative schedule: 2 chewable tablets every 30-60 minutes for overindulgence symptoms 1
- Maximum daily dose: 8 doses (approximately 4.2 g bismuth subsalicylate) in 24 hours 1, 2
- Duration: Use until diarrhea stops but not more than 2 days 1
- Ensure adequate fluid intake to prevent dehydration 1
Helicobacter pylori Eradication (Bismuth Quadruple Therapy)
- Dose: 2 tablets or 2 capsules four times daily (q.i.d.) taken 30 minutes before meals 3
- Combination therapy: Given with tetracycline HCl 500 mg q.i.d., metronidazole 500 mg q.i.d. (both 30 minutes after meals), plus a proton pump inhibitor twice daily 3
- Duration: 14 days 3
- Alternative regimen: 2 tablets or capsules q.i.d. 30 minutes before meals with tetracycline HCl 500 mg twice daily and metronidazole 500 mg q.i.d. after meals 3
Pediatric Dosing
Children under 12 years: Consult a physician before use 1. The FDA label does not provide specific pediatric dosing recommendations for over-the-counter use, emphasizing the need for medical supervision in this age group.
Safety Considerations
Salicylate Absorption and Toxicity Risk
- Salicylate from bismuth subsalicylate is extensively absorbed (>90%) from the gastrointestinal tract 2
- The maximum daily dose of 4.2 g produces peak plasma salicylate concentrations well below toxic levels 2
- After a 60 mL dose, peak plasma salicylate levels average 40.1 ± 17.3 mcg/mL, reached within 0.5-3 hours 4
- Approximately 95% of salicylic acid equivalents are recovered in urine 4
Bismuth Absorption
- Minimal bismuth absorption occurs (<0.005%) from the gastrointestinal tract 2
- Extended dosing for up to 6 weeks produces mean blood bismuth concentrations of 16.1 ± 7.9 ng/g, well below neurotoxic levels 2
Duration Limits
- Acute use: Safe for short-term symptomatic relief (up to 2 days for diarrhea) 1
- Extended use: Can be used safely for up to 3-4 weeks when medically indicated (such as H. pylori treatment) 2
- Do not exceed recommended duration without medical supervision 1
Clinical Efficacy Context
- Bismuth subsalicylate at 30 mL every 30 minutes for 8 doses significantly reduces diarrhea frequency compared to placebo 5
- The standard 4.2 g daily dose over 3.5 hours reduces stool frequency and improves subjective symptoms in traveler's diarrhea 6
- For acute diarrhea, loperamide provides faster relief than bismuth subsalicylate, though both are effective 7